1. Field of the Invention
The present invention generally relates to a data management information obtaining method, an information reproducing device, a data management information obtaining program, and a recording medium, and more particularly, to a data management information obtaining method for obtaining management information concerning a recording of data recorded on each of data areas divided in a recording area of an information recording medium, an information reproducing device using the data management information obtaining method, a data management information obtaining program for causing a control computer of the information reproducing device to perform the data management information obtaining method, and a recording medium storing the data management information obtaining program.
2. Description of the Related Art
Recently, personal computers have been provided with improved functions, such as a function of dealing with AV (Audio-Visual) information concerning music and video images. Since the AV information amounts to a considerably large extent, optical discs, such as a CD-R and a DVD+R, have come to attract attention as information recording media for recording such AV information. Further, as such optical discs have become inexpensive, optical disc devices as information reproducing devices have become widespread as peripheral devices for a personal computer.
Recordable optical discs, such as a CD-R and a DVD+R, adopt a file system conforming to a sequential UDF (Universal Disc Format) standard. In a recording area of such an optical disc, data is recorded sequentially in recording units referred to as tracks (or fragments for DVD+R). Further, a lead-in and a lead-out are added to an area composed of the tracks so as to form a session. Besides, hereinbelow, the term “track” is sometimes used for representing not only a track but also a fragment, for convenience' sake.
For example, a recording area of a DVD+R accommodates a maximum of 191 sessions, and each of the sessions is capable of storing a maximum of 16 fragments. That is, a DVD+R can include a maximum of 3056 (191×16) fragments. Besides, in a DVD+R, a lead-in of a second session and after is referred to as an Intro, and a lead-out of a second last session and before is referred to as a Closure. Additionally, an area referred to as a session disc control block (SDCB) provided in a lead-in (or an Intro) of each session stores information concerning individual fragments of the session (hereinafter referred to as “fragment information” which includes a fragment number, and a start address and a final address of the fragment). Further, the SDCB includes not only the fragment information concerning all of the fragments in the session, but also information concerning each of sessions preceding the present session which includes session numbers, a start address and a final address of each session.
In addition, a host device (e.g., a personal computer) needs information concerning a recording of data recorded on an optical disc prior to reproducing the data from the optical disc. Therefor, the host device requests an optical disc device to provide data management information including information concerning sessions existing in the optical disc (hereinafter referred to as “session information” which includes the number of sessions included in a recording area) and information concerning tracks (hereinafter referred to as “track information” which includes the number of tracks included in the recording area and track addresses indicating recording positions of the tracks).
Then, for example when the optical disc is DVD+R, the optical disc device informs the host device of the above-mentioned fragment information in response to the request from the host device for the track information. Otherwise, when the optical disc is CD-R, the optical disc device obtains a response to the request from the host device for the track information, based on track information recorded in an area referred to as a program memory area (PMA).
However, for example when the optical disc is DVD+R, since the fragment information is recorded in the SDCB of each session, the conventional optical disc device has to sequentially search the SDCBs of the sessions distributed in the recording area upon receiving the request from the host device for the track information. Thus, the conventional optical disc device has an inconvenience of considerably deteriorated performance, i.e., a considerably decreased response speed with respect to the request from the host device for the track information.
Thereupon, it is conceivable that the conventional optical disc device may obtain beforehand all the fragment information upon insertion of the optical disc thereinto. However, as mentioned above, the conventional optical disc device requires a considerably long time to obtain all the fragment information; thus, there is an inconvenience of an increased disc mount time, which forces a user to wait for a long time to access the optical disc after inserting the optical disc into the optical disc device. Further, as mentioned above, since the DVD+R can include 3056 fragments at the maximum, it is difficult to store the fragment information of all of these fragments, in consideration of memory capacity.